1. Field of the Invention
This invention is concerned with alkylation of aromatic compounds and, in particular, it is directed to a method for production of relatively long chain length phenylalkanes.
2. Description of the Prior Art
Conventional Friedel-Crafts alkylations of aromatic compounds with linear olefins, carried out in the presence of AlCl.sub.3 or other Lewis acid as catalyst, are known to produce linear secondary phenylalkanes which are typically a mixture of all of the conceivable positional isomers--i.e. 2-phenyl, 3-phenyl, 4-phenyl, etc. Primary phenylalkanes and products with side chain branching are not usually formed. For example, the reaction of benzene and 1-dodecene in the presence of AlCl.sub.3 gives a product mix as follows:
______________________________________ ##STR1## Position of Phenyl Substituent, # Composition ______________________________________ 1 0% 2 30% 3 19% 4 17% 5 17% 6 17% ______________________________________
The composition of the phenyldodecane mixture is somewhat dependent upon the acid catalyst involved. For instance, H.sub.2 SO.sub.4 catalyst has been reported to result in 41% 2-phenyldodecane while HF yields 20% 2-phenyldodecane in the phenyldodecane product mix. Similar results can be shown for other alkylations involving relatively large (i.e. &gt;C.sub.5) alkylating agents.
Commercial production of linear alkylbenzenes by the Friedel-Crafts route presently exceeds 500 million pounds per year. The vast majority of this production is subsequently sulfonated to produce alkylbenzene sulfonic acids for the detergent industry. Other known routes for alkylation of benzenes with long chain alkylating agents include utilization of acidic ion exchange resins and of faujasites. Highly acidic faujasites such as REY and REX have been shown to be potentially useful by the work of P. B. Venuto et al published in the JOURNAL OF CATALYSIS, 4, 81-98 (1966).